A concise review on alternative route of biodiesel production via interesterification of different feedstocks

Abstract

Environmental challenges and decreasing fossil reserves due to increased utilization of fossil fuels have propagated the importance of alternative energy sources. Increased biodiesel production promoted excess waste crude glycerol leading to environmental issues, thereby inhibiting the sustainability of the process. This review paper discusses the different types of feedstocks utilized to produce glycerol-free biodiesel by reacting with methyl acetate via interesterification. Methyl acetate is used as an advantageous alternative to methanol in biodiesel production to overcome the environmental challenge associated with excess waste glycerol. The by-product, triacetin from the interesterification reaction, has shown excellent qualities as a fuel additive, thereby making the process cleaner and more sustainable as a result of not separating the triacetin from biodiesel. The resulting product referred to as biodiesel fuel (BDF) has been found to exhibit useful properties and applications as fatty acid methyl esters (FAME). The promising environmental and sustainability merits of the process far outweigh the slow interesterification kinetics demerits of the process, which can be overcome by suitable processing conditions. The prospects associated with biodiesel production by interesterification are also pointed out.

Techno-Economic Analysis of Interesterification for Biodiesel Production

“…A global shortage of fossil fuel-derived energy, which accounts for 80% of the global energy supply, 1 has increased the relevance of renewable energy. Fatty acid alkyl esters (FAAEs, commonly used as biodiesel) can serve as a drop-in alternative to fossil fuel-based diesel fuel in compression−ignition engines.…”

Interesterification of triglycerides with methyl acetate for biodiesel production using a cyclodextrin-derived SnO@γ-Al2O3 composite as heterogeneous catalyst

“…The current energy system for transportation is still based on fossil fuels whose utilization is not sustainable in the long term due to limited resources and negative impact on climate change related to the accumulation of CO2 in the atmosphere [1]. For these reasons, fossil fuels must be gradually substituted by other CO2 neutral renewable energetic sources.…”

“…Another drawback of the transesterification is that methanol, which is used as acyl acceptor, is insoluble in the reaction media; therefore the alcoholysis generally starts with high interfacial mass transfer resistances that require accurate mixing. Recently, it was also found that methanol could be incompatible with the long-term stability of several heterogeneous catalytic systems, therefore making the overall process less effective [1].…”

“…Many studies were conducted in the last years to investigate the potentiality of the interesterification in order to optimize the operative parameters and the performances of the catalytic system. Some of them evidence that this reaction could be performed without added catalysts,using supercritical methyl acetate [1,[11][12][13][14][15] or ethyl acetate [16,17] as acyl donnors, but the high-temperature and highpressure conditions reduce the process flexibility. Other studies report that the interesterification can be conducted at room temperature using alkaline hydroxide and/or alkoxides as homogeneous catalysts [18][19][20][21][22][23][24][25].…”

“…In this context, chemical heterogeneous interesterification has aroused as an interesting alternative since it offers the advantage of producing high FAME yields in short reaction times and the possibility to regenerate and reuse the catalyst, therefore reducing the operation costs. From the literature on this field, it seems however that interesterification usually requires longer reaction times with respect to transesterification to reach equivalent FAME yields [1]. Phenyl-sulfonic acid-functionalized SBA-15 catalyst [34],nobium phosphate, nobium oxide, γ-alumina and zeolite HY [35,36], together with mixed oxides [37] and hydrotalcites [38], were investigated as heterogeneous catalysts in the interesterification of several raw materials at different operational conditions.…”